import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] sticks = new int[n];
        for (int i = 0; i < n; i++) {
            sticks[i] = sc.nextInt();
        }
        Arrays.sort(sticks);
        long k = sc.nextLong();
        if (n >= k) {
            System.out.println(sticks[n - (int)k]);
        } else {
            double left = sticks[0] / (double)(k / n + 1);
            double right = sticks[n - 1] + 1;
            for (int i = 0; i < 10000; i++) {
                double m = (left + right) / 2;
                long sum = 0;
                for (int j = 0; j < n; j++) {
                    sum += (long)(sticks[j] / m);
                }
                if (sum >= k) {
                    left = m;
                } else {
                    right = m;
                }
            }
            System.out.println(left);
        }
    }
}